Process of making an improved resilient fabric



May 7, 1957 c. R. ANDERSON PROCESS OF MAKING AN IMPROVED RESILIENTFABRIC Filed March 26, 1953 2 Sheets-Sheet l INVENTOR. OIRROL 1. R.4/voERs0/v ATTORNEYJ" May 1957 c. R. ANDERSON 2,791,021

PROCESS OF MAKING AN IMPROVED RESILIENT FABRIC Filed March 26, 1953 2Sheets-Sheet 2 HEAT/N6 Q) 2 g 3 I 3 1,: k

I I INVENTOR.

CARROLL R. ANDERSON ATTORNEYS United States Patent PROCESS OF MAKING ANIMPROVED RESILIENT FABRIC Carroll R. Anderson, Minnetonka Beach, Minn.,assignor to Munsingwear, Inc., Minneapolis, MIIIIL, a corporation ofDelaware Application March 26, 1953, Serial No. 344,790

16 Claims. (Cl. 26-68) This invention relates to a process of making animproved resilient fabric and more particularly to a process of makingan improved resilient fabric from linear polyamide yarns for use ingarment structures composed completely or partially of such fabrics.This application is a continuation-in-part of my copending applicationSerial No. 190,990, filed October 19, 1950, now Patent No. 2,636,368issued April 28, 1953.

In many garments it is desirable to construct the whole garment orportions of the garment from fabrics having a resilient characteristicin one or more directions. Prior to the invention in my applicationSerial No. 190,990 aforesaid and this invention, many commercialgarments have been constructed of fabrics knitted from rubber-elasticyarns. Such rubber-elastic yarns are knitted under tension and afterknitting the yarn tends to contract and the fabric accordingly assumes asmaller size in its relaxed condition than when under tension across thefabric. Such fabrics made of rubber-elastic yarns knitted under tensionare well known and have a great usefulness but unfortunately are subjectto relatively short life and frequently do not perform their functionthroughout the normal life of the garment. Knitted resilient orstretchable" fabrics made from rubber-elastic yarn have been the bestavailable for use in such garments as girdles, in the waist bands ofpajamas, shorts, wristlets and the like prior to the invention of myaforesaid application.

The principal disadvantage of fabrics knitted from rubber-elastic yarnsis that the elastomer which is used as the resilient base of the yarn,whether of natural or synthetic type, is subject to short life andaccordingly a garment composed of such materials may lose its stretch ina matter of months of wear or even during shorter times. Furthermore,the deterioration occurs on the shelf and in order to obtain the mostservice from such garments they must be merchandised and used within areasonable time after being made. Such stretchable fabrics made ofrubber-elastic yarns, regardless of whether the rubber is natural orsynthetic, are particularly subject to deterioration due to laundering,for water and detergents markedly reduce the life of such elasticmembers. Since laundering is essential in the use of most fabrics thatare used for body garments, this reduction in life of the garment due tolaundering has had to be accepted as one of the inherent limitations ofsuch fabrics. The heat encountered in drying the laundered garment andin ironing cause further deterioration of the elastic yarns.

It is a principal object of this invention, therefore, to provide animproved process of making a resilient fabric having long service life.

It is another object of this invention to provide a process of making animproved resilient fabric knitted from yarns composed of polyamidecondensation products, said yarns being selected from a specified rangeof 2,191,024 Patented May 7, 1 957 'ice sizes and having a ratio of thenumber of filaments to the denier size of the yarn in a specified ratiorange.

It is another object of this invention to provide a process for treatingelastic fabrics knitted from yarns composed of polyamide condensationproducts for the purpose of improving and enhancing their resiliency,and to provide improved knitted fabrics so treated.

Other objects will become apparent as the description proceeds.

Broadly stated, the invention comprises a process of making animprovedresilient fabric which includes the steps of treating a fabricknitted from a yarn made up of a plurality of filaments composed of alinear condensation polymer by subjecting this knitted fabric toeittreme tension in the direction of knitting and then while sotensioned, heating said stretched fabric.

The invention is illustrated with reference to the drawings in whichcorresponding numerals refer to the same parts and in which:

Figure 1 is an enlarged fragment of a representative fabric made inaccordance with the instant invention;

Figure 2 is a side elevational view of a diagrammatic representation ofone form of apparatus for carrying out this invention; t.

Figure 3 is a fragmentary perspective view of one form of tensioningmeans.

In carrying out the invention there are utilized yarns composed oflinear condensation polymers made in accordance with one or more of thefollowing patents: 2,071,250 through 2,071,253; 2,130,523; 2,130,948; 214-9,286 and 2,149,273. Fiber forming polyamide yarns, such as nylon,have especial usefulness in this invention. Throughout thisspecification and in the claims, the term linear condensation polymeryarns will be understood to include yarns made in accordance with theaforesaid patents and more especially fiber forming polyamide yarns,such as nylonyarns. Such linearcondensation polymer yarns are the yarnsof commerce and are pro stretched by the yarn manufacturer, in whichprestretched condition they are sold in commerce. Thus, commercial nylonyarns of appropriate denier size and filament count, as hereinafterdescribed and ready for knitting may be used.

In carrying out the invention the fabric isknitted utilizing such linearcondensation polymer yarn having a denier size in the range of to 300,,said yarns being composed always of a plurality of filaments. The numberof filaments in the yarn must be such that the ratio of the number offilaments divided by the denier size number is in the range from 0.02 to0.15. Best results are obtained when the ratio of the number offilaments in such yarn to the denier size number is in the preferredrange of 0.03 to 0.10. The knitted fabric is preferably a 1 x 1 rib knitfabric, but other knitted fabrics such as the Swiss knit fabric may alsobe used, although the 1 X 1 rib knitfabric is preferred because of itsinherent greater stretch resistance transversely of the direction ofknitting.

Thus, in accordance with the invention the fabric may be knitted fromyarns composed of the stated linear condensation products in the sizerange from 100 to 300. For example, yarns having a denier size of'100and having from 2 to 15 filaments are satisfactory where it is desiredto have a fabric which stretches easily with low pull, the stretch, ofcourse, knitting. Whereit is desired to have a fabric which, thoughelastic (in the direction transverse to the direction of knitting) yetrequires more force (pull) to cause the stretching, the yarn size shouldbe increasedto, for example, 200 denier size and having a number offilaments ranging from about 4 to about 30. Likewise, wherestill greaterstrength is needed, while still preserving the being transverse to thedirection of is subjected to a tensioning and heating treatment.

fabric is tensioned by stretching in the direction of knitcharacteristicof elasticity transverse to the knitting direction, yarns of size 250denier and having a number of filaments from about 5 to about 38-40 aresatisfactory. For maximum transverse elastic strength, yarns of 300denier size are utilized having a number of filaments ranging from about5 to about 45. It will be appreciated that the number of filaments inthe yarn may be varied somewhat out of the stated ranges and likewiseslightly larger or smaller denier sizes than those stated may beutilized. For best results, however, the ratio of the number offilaments to the denier size number should be held in the approximaterange of 0.02 to 0.15 and the denier size should be from about 100 toabout 300.

In order to set the inherent resiliency of the above fabrics knittedfrom yarns as specified, the knitted fabric The ting. Ordinarily, knitfabric has relatively little elasticity in this direction. The tensionwhich is applied is extreme, being just short of that which. willrupture the filaments of the yarn. This will, in most cases, be tensionsufficient to provide an elongation of the knitted fabric in the rangeof from about 12% to 20%. Thus, the

fabric knitted from one of the specified yarns is stretched by tensionin the direction the fabric is knitted (applied substantially uniformlyacross the width of the fabric) until the increase in length fromrelaxed condition of the fabric to stretched condition is about 12% toabout 20%. While in this stretched condition the fabric is subjected toheat in the range from about 200 to 425 F. Thereafter the tension may berelaxed and the fabric will remain KISBt'QI treatment, the fabric willremain permanently elongated in the range of from about 7% to 15%.

Becausenylon filaments are relatively impervious to moisture the heatmay be applied either dry or moist. The use of superheated steam istherefore a convenient It will be found that after the tensioning (withconsequent stretching) and accompanied by the heating means of attainingthe desired temperature conditions.

. When moist heatis used, it will, of course, be necessary to subjectthe treated fabric to a drying step. This may beeither before or afterthe tension on the fabric is relaxed. Afrange from about 250 to 400 F.provides the preferred temperature conditions for achieving permanentset? of the knitted fabrics of this invention.

The tensioning and heating treatments of this invention are not to beconfused with the so-called cold drawing through which polyamidefilaments are customarily subjected in the process of their formation,nor to the ironing or boarding treatments to which finished woven orknitted fabrics are customarily subjected. Filaments of linearcondensation polymers are customarily subjected to cold drawing in thecourse of their preparation. This stretching in the solid state causesfundamental physical changes to take place in the filament impartinggreater strength and pliability to the fibers. Alternatively, thefilaments may be stretched after they are twisted into yarns. It is.contemplated that the commercial yarns which are used in the initialknitting step of this invention will have already been subjected to sucha preliminary stretching treatment by the yarn manufacturer. If thefilamentsor the yarns have not been thus pro-stretched, this treatmentis applied before the knitting operation is undertaken.

Before marketing knitted wear it is customary to scour the fabric in ahot soap solution, rinse the fabric and then iron or board it. This isdone to give the fabric a neatly pressed appearance. One means ofboarding fabrics composed of yarns of linear condensation polymers is toiron it in the presence of superheated steam at temperatures of about100 C. to 150 C. This treatment differs from the treatment of theinstant invention, however, in that it is carried out under minimumtension usually applied transversely of the knitting direction and in anamount merely sufiicient to hold the fabric smooth while it is beingironed. The treatment of this invention is carried out under extrememaximum tension applied in the direction of knitting.

Referring now to the drawings and particularly to Fig ure 1, there isshown here an enlarged fragment of a representative fabric 1 made inaccordance with the instant invention. The direction of knitting isshown by double arrow NS and the direction transverse to the directionof knitting is shown by double arrow S. The fabric readily stretches inthe direction of the double arrow S and stretches very little in thedirection of double arrow NS. Accordingly, when the fabric of Figure lis used in a garment, it is laid so that the direction S will correspondto the direction in the garment in which resiliency is desired.

In Figure 2 there is shown diagrammatically a side elevational view ofone form of apparatus by which the instant invention can be carried out.A length of fabric 1 is fed out of hamper 2 in the direction of knittingover guide roll 3, under adjustable drag bar 4, around adjustable dragbar 5, around bar 4 and over bar 5, under guide roller 6, over guideroller 7, under guide roller 8, over guide roller 9 and between drivenhorizontal transverse rollers 10 for producing slight (smoothing)tension across the fabric, thence passing between heaters, hereillustrated as two pairs of steam boxes 1213 and 14-15 to heavy drivencalender pull and tensioning rollers 16 and 17 and thereafter over guideroller 18 to hamper 19. The fabric is maintained under tension betweendrag bars 4 and 5 and calender rolls 16 and 17 which do the pulling.Restraint to movement of the fabric is adjustably applied by the dragbars 4 and 5 which are shown in more detail in Figure 3. The means forinitially restraining the fabric comprises parallel bars 4 and 5 fixedlymounted at their ends to either end of bars 20, forming a frame which inturn is pivotally mounted on tnmnions 21 in a frame of the apparatus notshown. The frame may be pivotally adjusted in the direction of doublearrows 22--22 and locked in any adjusted position by clamps (not shown)so as to adjust the amount of tension or drag imposed on the fabric. Thefabric is threaded under bar 4, around bar 5, thence around bar 4 andover bar 5. It is readily seen that by rotating the frame 420-20-5clockwise about its pivot 21 (as viewed in Figures 2. and 3) the tensionon the fabric will be decreased and vice versa. Then the desired tension(or frictional drag) is applied to the fabric, the entire frame is fixedin its adjusted position. It will be apparent that suitable tensioningrollers may be used in lieu of drag bars 4 and 5. Likewise, otherheating elements, such as gas fired or electrically heated elementsmaybe used instead of steam boxes 13 through 15. Where such dry forms ofheating are used, the drying zone may be considerably shortened or eveneliminated. It will also be apparent that the fabric may readily be feddirectly from the knitting machine into the treating apparatus used tocarry out this invention.

The fabric forming the waist band or other elastic member of a garmentmay be knitted either as a tubular knit fabric or a flat knit fabric,the tubular knit being preferred for such applications as underwear,waist bands, wristlets, etc. The fabric is preferably knit in a varietyof tubular sizes corresponding to the various garment sizes to which thefabric is applied, thus dispensing with any seams vertically through thefabric when applied, for example, as a waistband. However, such avertical seam is of no particular disadvantage where, for example, it isdesired to make a belt opening.

The invention is further illustrated with reference to the followingspecific example:

A tubular fabric was knitted from nylon yarn of 260 denier having 17filaments on a conventional tubular knitting machine. The ratio of thenumber of filaments divided by the denier size was 0.065. This fabricwas then fed into a conventional calender (Tube-tex; Tubular TextileMachinery Company, Woodside, Long Island, New York) at the rate of 3.14inches per second. The fabric was fed through the calender in thedirection of knitting and held taut transversely of the direction offeed. For this there is used the mechanism including an inner tensioningframe which imposed just sufficient tension transversely of thedirection of knitting (direction S of Figure 1) so as to hold the fabricflat and avoid wrinkles. This tensioning mechanisrn'is a part of theTube-tex machine. Simultaneously the fabric was held under extremetension (in the knitting direction NS, Figure 1), such tension beingsufi icient to impart about 18% elongation to the fabric, and while thustensioned the fabric was subjected to superheated steam having atemperature of about 265 F. to 270 F. and to heat radiated from heaters1215.- The actual temperature of the fabric at A in Figure 2 of thedrawing was 230 F., at B 250 F. and at C 260 F. The heated stretchedfabric was then passed through the heavy calender and draw rolls 16 and17 which produced the extreme tension lengthwise of the fabric, and alsoironed the fabric. Thereafter the tension was relaxed and the fabric wasdried. As a measure of the elongation produced in the direction ofknitting by the extreme tension it may be noted that the fabric beforetreatment had 39-40 courses per inch in the direction of knitting. Thesame fabric after treatment had 35-36 courses per inch in the directionof knitting. Thus, it is seen that a permanent elongation of 11.2% wasimparted to that fabric by the extreme tension in the direction ofknitting and heating. Also, the untreated fabric could be stretched byhand in the direction of knitting about 12 to but the treated fabriccould be stretched only about 5%.

It is apparent that many widely different embodiments of this inventionmay be carried out without departing from the spirit and scope thereof.It is to be understood, therefore, that the invention is limited not tothe specific embodiments thereof, but only by the. terms of the appendedclaims.

What I claim is:

1. A process of making an improved resilient fabric which comprisestreating a fabric rib-knit from a yarn made up of a plurality offilaments composed of a linear condensation polymer, the size of suchyarn being in the range of about 100 to 300 denier and the number offilaments in said yarn being so selected that the ratio of the number offilaments divided by the denier size is in the range of 0.02 to 0.15, bysubjecting said knitted fabric to extreme tension in the direction ofknitting sufficient to provide in the range of about 12 to 20 percentelongation and heating said stretched fabric to from 200 to 425 F.

2. A process of making an improved resilient fabric which comprisestreating a fabric rib-knit from a yarn made up of a plurality offilaments composed of a linear condensation polymer, the size of suchyarn being in the range of about 100 to 300 denier and the number offilaments in said yarn being so selected that the ratio of the number offilaments divided by the denier size is in the range of 0.02 to 0.15, bysubjecting said knitted fabric to slight tension transverse of thedirection of knitting sufficient to hold the fabric smooth and free ofwrinkles and to extreme tension in the direction of knitting sufficientto provide in the range of about 12 to 20 percent elongation and heatingsaid stretched fabric to from 200 to 425 F.

3. A process of making an improved resilient fabric which comprisestreating a fabric rib-knit from a yarn made up of a plurality offilaments composed of a linear condensation polymer, the size of suchyarn being in the range of about 100 to 300 denier and the number offilaments in said yarn being so selected that the ratio of the number offilaments divided by the denier size is in the range of 0.02 to 0.15, bysubjecting said knitted fabric to extreme tension in the direction ofknitting suificient to provide the range of about 12 to 20 percentelongation, heating said stretched fabric to from 200 to 425 F., andrelaxing the tension on said stretched fabric.

4. A process of making an improved resilient fabric which comprisestreating a fabric rib-knit from a yarn made up of a plurality offilaments composed of a linear condensation polymer, the size of suchyarn being in the range of about to 300 denier and the number offilaments in said yarn being so selected that the ratio of the number offilaments divided by the denier size is in the range of 0.02 to 0.15, bysubjecting said knitted fabric to extreme tension in the direction ofknitting sufiicient to provide the range of about 12 to 20 percentelongation, subjecting the stretched fabric to moist heat in the rangeof about 200 to 425 F., relaxing the tension on said stretched fabricand then drying.

5. The process of claim 4 in which the moist heat is applied bysteaming.

6. The process of claim 5 in which the stretched fabric is heated in therange of about 250 to 400 F. by applying superheated steam to thefabric.

7. A process of making an improved resilient fabric which comprisestreating a fabric rib-knit from a yarn made up of a plurality offilaments composed of a linear condensation polymer, the size of suchyarn being in the range of about 100 to 300 denier and the number offilaments in said yarn being so selected that the ratio of the number offilaments divided by the denier size is in the range of 0.03 to 0.10, bysubjecting said knitted fabric to extreme tension in the direction ofknitting sufficient to provide in the range of about 12 to 20 percentelongation and heating said stretched fabric to from 200 to 425 F.

8. A process of making an improved resilient fabric which comprisestreating a fabric rib-knit from a yarn made up of a plurality offilaments composed of a linear condensation polymer, the size of suchyarn being in the range of about 100 to 300 denier and the number offilaments in said yarn being so selected that the ratio of the number offilaments divided by the denier size is in the range of 0.03 to 0.10, bysubjecting said knitted fabric to slight tension transverse of thedirection of knitting sufiicient to hold the fabric smooth and free ofwrinkles and to extreme tension in the direction of knitting sufficientto provide in the range of about 12 to 20 percent elongation and heatingsaid stretched fabric to from 200 to 425 F.

9. A process of making an improved resilient fabric which comprisestreating a fabric rib-knit from a yarn made up of a plurality offilaments composed of a linear condensation polymer, the size of suchyarn being in the range of about 100 to 300 denier and the number offilaments in said yarn being so selected that the ratio of the number offilaments divided by the denier size is in the range of 0.03 to 0.10, bysubjecting said knitted fabric to extreme tension in the direction ofknitting sufficient to provide in the range of about 12 to 20 percentelongation, heating said stretched fabric to from 200 to 425 F., andrelaxing the tension on said stretched fabric.

10. A process of making an improved resilient fabric which comprisestreating a fabric rib-knit from a yarn made up of a plurality offilaments composed of a linear condensation polymer, the size of suchyarn being in the range of about 100 to 300 denier and the number offilaments in said yarn being so selected that the ratio of the number offilaments divided by the denier size is in the range of 0.03 to 0.10, bysubjecting said knitted fabric to extreme tension in the direction ofknitting sufiicient to provide in the range of about 12 to 20 percentelongation, subjecting the stretched fabric to moist heat in the rangeof about 200 to 425 F., relaxing the tension on said stretched fabricand then drying.

11. The process of claim 10 in which the moist heat is applied bysteaming.

12. The process of claim 11 in which the stretched fabric is heated inthe range of about 250 to 400 F. by applying superheated steam to thefabric.

13. A process of making an improved resilient rib-knit fabric whichcomprises treating a tubular fabric knit from a yarn made up of aplurality of filaments composed of a linear condensation polymer, thesize of such yarn being in the range of about 100 to 300 denier and thenumber of filaments in said yarn being so selected that the ratio of thenumber of filaments divided by the denier size is in the range of 0.02to 0.15, by subjecting said knitted fabric to extreme tension in thedirection of knitting sufficient to provide in the range of about 12 to20 percent elongation and heating said stretched fabric to from 200 to425 F.

14. The process of claim 13 further characterized by being continuous.

15. A process of making an improved resilient nylon fabric Whichcomprises treating a tubular fabric rib-knit from a yarn made up from amultiple filament yarn composed of a fiber-forming polyamide material,the denier number of said yarn being substantially 260 and the number offilaments in the yarn being approximately 17, by subjecting said tubularknitted fabric to extreme tension in the direction of knittingsufficient to provide from about 12 to 20 percent elongation, subjectingsaid Miami-uneasy; t a

stretched fabric to superheated steam in the range of about 250 to 400F., relaxing the tension on said stretched fabric and drying, wherebythe tubular knitted fabric is permanently elongated in the direction ofknitting in the range of from about 7 to 15 percent and its resiliencyimproved thereby.

16. As a new product, the improved resilient rib-knit fabric producedaccording to the process of claim 1.

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